1,3,3-TRIMETHYL-BIS ({60 -t-BUTYLPEROXYISOPROPYL)-1-PHENYLINDANE

ABSTRACT

1,3,3-Trimethyl-bis( Alpha -t-butylperoxyisopropyl)-1phenylindanes in which the Alpha -t-butylperoxyisopropyl groups are attached in the 6- and 4&#39;&#39;-, 6- and 3&#39;&#39;-, 5- and 4&#39;&#39;-, and 5and 3&#39;&#39;-, 7- and 4&#39;&#39;-, or 7- and 3&#39;&#39;-positions are heated in contact with curable polymers whereby crosslinking of the polymer is effected.

United States Patent Schappell 1 June 6, 1972 [5 1,3,3-TRIMETHYL-BIS (a-t- BUTYLPEROXYISOPROPYL)-l- References Cited PHENYLINDANE UNITED STATES PATENTS [721 memo Frederick schappell Newark, 3,402,205 9/1968 Gregory ..260/610 R [73] Assignee: Hercules Incorporated, Wilmington, Del.

Przmary Examiner-Bernard Helfin [22] Filed: Dec. 31, 1969 Assistant ExaminerW. B. Lone 1 pp No: 889,685 Attorney-Manon C. Staves 7 Related U.S. Application Data [57] ABSTRACT l,3,3-Trimethyl-bis(a-t-butylperoxyisopropyl)-l-phenylin- 163] fgg m pan of 74ll91ll1lyf2-" danes in which the a-t-butylperoxyisopropyl groups are attached in the 6- and 4-, 6- and 3-, 5- and 4-, and 5- and 3-, 7- and 4'-, or 7- and 3'-positions are heated in contact with [52] U.S. Cl ..260/610 B, 252/188.3, 260/875, curable polymers whereby crosslinking of the polymer is ef 260/949 GA fected [5 l Int. Cl ..C07c 73/06 [58] Field of Search ..260/610, 610 R 7 Claims, No Drawings 1,3,3-TRlMETHYL-BIS (a-T- BUTYLPEROXYISOPROPYL)- l -PHENYLINDAN E This application is a continuation-in-part of application, Ser. No. 741,850, filed July 2, 1968.

This invention relates to organic peroxides and, more particularly, to organic peroxides which are nonblooming, odorfree curing agents for olefin polymers, and to compositions capable of being crosslinked therewith.

In Us. Pat. No. 3,402,205 there is described a class of peroxides in which an aryl nucleus is substituted by two to four t-alkylperoxyisopropyl groups. The aryl nucleus was exemplified by groups containing either one benzene ring or more than one benzene ring joined together directly by fusion or by a single atom.

It has now been found that a bisperoxide of the formula is attached to a benzene ring is an organic peroxide having excellent curing properties for polyethylene and greater scorch resistance than related bisperoxides and is nonblooming.

The peroxides of this formula have the nucleus of an amethylstyrene dimer, i.e., A

and they can be made by isopropylating a-methylstyrene dimer to a diisopropyI-a-methylstyrene dimer, oxidizing the latter to a bis(a-hydroxyisopropyl)-a-methylstyrene dimer,

and reacting this last-named compound with t-butylhydroperoxide. The bisperoxides of this invention can also be made from isomers such as p-isopropyl-a-methylstyrene dimer, or from m-isopropyl-anethylstyrene dimer.

This group of bisperoxides is exemplified 7 113,3- trimethyl-6,4-bis(t-butylperoxyisopropyl)-l-phenylindane which is prepared by oxidizing the dimer of p-isopropyl-amethylstyrene, i.e., 1,3,3-trimethyl-6,4-bis(isopropyl)-lphenylindane to the dialcohol, l,3,3-trimethyl-6,4'- bis(hydroxyisopropyl)-l-phenylindane, and then reacting the dialcohol with t-butylhydroperoxide to form the 1,3,3- trimethyl-6,4 '-bis( t-butylperoxyisopropyl l -phenylindane.

The process of preparation and a description of the properties of this novel bisperoxide are illustrated in the following examples, in which all parts and percentages are by weight.

EXAMPLE 1 1,3 ,3-Trimethyl-6,4'-bis( isopropyl l -phenylindane was prepared by heating 100 parts p-isopropyl methylstyrene with 180 parts 80 percent aqueous sulfuric acid at 80-90 C.,

with stirring for 1 hour and recovered by separating the acid layer, washing the organic phase with dilute aqueous sodium hydroxide and water, and distilling to obtain 56 parts of 5 product which melted at 53-54 C.

1,3,3-Trimethyl-6,4'-bis( hydroxyisopropyl l -phenylindane was prepared by dispersing moist oxygen gas into 100 parts of l,3,3-trimethyl-6,4-bis(isopropyl)-l-phenylindane while rapidly stirring with 25 parts of 50 percent aqueous sodium hydroxide at ll0-l C. for about 10 hours and was purified by dissolving in benzene and washing free of salts of acidic materials with 4 percent aqueous sodium hydroxide, and subsequent countercurrent extraction of an acetonitrile solution thereof with hexane followed by distilling off the acetonitrile. 8' 8' 1,3 ,3-Trimethyl-6,4 -bis( t-butylperoxyisopropyl l -phenylindane was prepared by heating at 47-60 C. a solution of 32 parts l,3,3-trimethyl-6,4-bis(hydroxyisopropyll l-phenylindane, 37.2 parts 82 percent t-butylhydroperoxide and 0.38 part p-toluene-sulfonic acid in 100 parts heptane under reflux under reduced pressure with water removal for about 3 hours and, subsequently, purifying by washing with 8 percent sodium hydroxide and then with water and distilling ofi the heptane. The yield of bisperoxide was 12.4 percent of theory as shown by infrared and iodometric analyses.

A sample of the above l,3,3-trimethyl-6,4'-bis(t-butylperoxyisopropyl)-l-phenylindane was compounded with low density polyethylene at the rate of 1 part peroxide per hundred of polyethylene (1 phr) and also at the rate of 0.2 phr. The polyethylene compositions containing also 0.5 phr antioxidant (AgeRite Resin D-R. T. Vanderbilt Co. trademark for polymerized trimethyl dihydroquinoline) were then vulcanized by heating one part at 177 C. for 10 minutes, and another part at 188 C. for 10 minutes. The results on the product were shown by gel and swell tests as follows:

40 Crosslinker 10 min. 177C. 10 min. 188C.

Level Gel Swell Gel Swell A filled sample of polyethylene was similarly prepared and tested using 40 phr carbon black in addition to 0.5 phr antioxidant (AgeRite Resin D) and l and 2 phr bisperoxide. The test results were shown by gel and swell tests as follows:

bis(isopropyl)-l-phenylindane was prepared by heating 100 parts of m-isopropyl-a-methylstyrene with 25 parts of percent aqueous sulfuric acid at about C. with stirring for 1 hour. The product was recovered after dilution with parts of water to facilitate removal of the acid layer. After washing with aqueous sodium hydroxide and water, the organic layer was dried and distilled in the presence of potassium carbonate to yield 34 parts ofa liquid, boiling in the range l48-l58 C. at 0.85 torr. Gas chromatographic analysis showed the product contained 98.7 percent phenylindane compounds.

dane was prepared as in Example 1 by the action of oxygen on 25 parts of the hydrocarbon mixture in the presence of 100 parts of 50 percent aqueous sodium hydroxide. The reaction was performed at 1001 15 C. for about 9 hours, after which i 19.2 parts of diol mixture was purified and isolated as described in Example 1.

A mixture of l,3,3-trimethyl-5,3-bis(a-t-butylperoxyisopropyl)-1-phenylindane and 1,3,3-trimethyl-7,3-bis(a-tbutylperoxyisopropyl)-l-phenylindane was prepared by heating 12 parts of the diol mixture with 15 parts 82 percent t-butylhydroperoxide and 0.38 part p-toluenesulfonic acid in 50 parts heptane under reflux under reduced pressure for 1.75 hours. Purification of the final product was effected as in Example l. 7

EXAMPLE A mixture of six diisopropyl-a-methylstyrene dimers composed of the 6,4-; 6,3'-; 5,4'-; 5,3'-; 7,4-; and 7,3'-' diisopropylatedisomers were prepared by heating 100 parts of a 2:1 mixture of mand p-isopropyl-a-methylstyrene with 100 parts of 80 percent aqueous sulfuric acid with stirring at 90 C. for 1 hour. The product was worked up and distilled as in Example 2 to give 30 parts of an oil, boiling at l60-175 C. at 1.0-1.1 torr.

Oxidation of 25 parts of this mixture was performed as in Example 1 in the presence of 50 parts 50 percent aqueous sodium hydroxide at ll 15 C. for 1 1 hours. After the termination of the oxidation, the product was worked up and purified as in Example 1 to give 1 1 parts 1,3,3-trimethylbis( hydroxyisopropyl)-l-phenylindane (mixed isomers of diols).

1,3 ,3-Trimethyl-bis( a-t-butylperoxyisopropyl 1 -pheny1indane (mixed isomers) was prepared by heating at 456l C. a solution of 10 parts of the mixed diols, 15 parts 82 percent tbutylhydroperoxide, 0.38 parts p-toluenesulfonic acid and 50 parts heptane under reflux under reduced pressure with water removal for 2 hours. Purification of the final product was effected as in Example 1.

EXAMPLE 4 A formulation of EPM 100 parts) 75 phr MT Black, 5 phr zinc oxide and 2.35 parts of the bisperoxide of Example 1 was prepared and compared with a similar formulation using 2.7 phr dicumylperoxide and, also, with a similar formulation using 1.7 phr m-bis(a-t-butylperoxyisopropyl)benzene. These formulations are designated 4A, 4B and 4C, respectively. The compositions 4A, 4B and 4C were separately mixed on a tworoll mill and were sheeted into test strips from which samples were cut for vulcanization testing on the Monsanto Oscillating Disk Rheometer. This rheometer is a device which measures dynamic properties, curing, and processing characteristics of elastomer compositions during the curing cycle. The sample from the test strip (4A, 4B and 4C) was placed in the device, and a disk embedded in the sample was subjected to oscillatory motion by a motor driven eccentric wherein the force (torque) required to oscillate the disc could be measured electronically while heating at controlled temperatures. The tests were carried out at 320 F. and 330 F. The first torque measurement taken was the minimum reached at initial equilibrium before cure began, T-min. Subsequent torque measurements were taken at intervals of time so as to be able to plot a curve of torque against time. The test was stopped at the time that maximum torque (T-max.) was reached. The time (t+l) to reach minimum torque (T-min.) plus 1 torque unit and the time to reach 90 percent of T-max. was also noted. The results were as follows:

Temperature (F.) T-min. T-max. T t+l t These results show that the compound of this invention (4A) requires a longer time for T to be reached, and this is indicative that the compound of this invention has a longer half-life than either of the related peroxides of 4B or 4C. The lower scorch resistance of the compound is attributed to the longer half-life. The longer half-life is also advantageous in controlling extent of curing of the polymer compositions.

ln crosslinking of crosslinkable polymers in accordance with this invention, the crosslinkable polymer is admixed with the bisperoxide of the present invention by any of the usual techniques conventionally employed in the elastomer field, as, for instance, by passage through mixing rolls or by dispersion usin conventional mixers. t

T e crosslinkable polymers WhlCh are particularly used In this process are polyethylene, natural rubber, polystyrene, polyisoprene, cis-4-polybutadiene, poly(chloroprene), silicone rubber, EPM, EPDM, SBR, and NBR. These may be unfilled or filled with the usual black and non-black fillers useful in compounding of these polymers.

EPM is an elastomeric ethylene--propylene copolymer and EPDM is an elastomeric terpolymer of ethylene, propylene and a diene such, for example, as l,4-hexadiene and dicyclopentadiene. The letter M in the above designation indicates elastomers having a saturated chain of the polymethylene typesee ASTM Designation: D 14l867.

NBR is nitrile-butadiene rubber. SBR is styrene-butadiene rubber.

What I claim and desire to protect by Letters Patent is: 1. A compound of the formula is attached to a benzene ring.

2. A compound of claim 1 in which a t-butylperoxyisopropyl group is attached to each benzene ring.

3. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 6 and 4'.

4. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 5 and 3.

5. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 7 and 3 6. A mixture of isomeric compounds of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 5 and 3' in one isomer and at 7 and 3 in the other.

7. A mixture of isomeric compounds of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 6 and 4', 6 and 3, 5 and 4, 5 and 3'7 and 4', and 7 and 3. 

2. A compound of claim 1 in which a t-butylperoxyisopropyl group is attached to each benzene ring.
 3. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 6 and 4''.
 4. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 5 and 3''.
 5. A compound of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 7 and 3''.
 6. A mixture of isomeric compounds of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 5 and 3'' in one isomer and at 7 and 3'' in the other.
 7. A mixture of isomeric compounds of claim 2 in which the t-butylperoxyisopropyl groups are attached at positions 6 and 4'', 6 and 3'', 5 and 4'', 5 and 3'' 7 and 4'', and 7 and 3''. 